05000341/LER-2015-002, Regarding Loss of Both Divisions of the Residual Heat Removal Low Pressure Coolant Injection Functions Due to 480 Volt Swing Bus Inoperable

Regarding Loss of Both Divisions of the Residual Heat Removal Low Pressure Coolant Injection Functions Due to 480 Volt Swing Bus Inoperable

ML15127A175
Person / Time
Site:	Fermi
Issue date:	05/07/2015
From:	Kaminskas V DTE Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NRC-15-0051 LER 15-002-00
Download: ML15127A175 (5)

LER-2015-002, Regarding Loss of Both Divisions of the Residual Heat Removal Low Pressure Coolant Injection Functions Due to 480 Volt Swing Bus Inoperable

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(vii)(A), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3412015002R00 - NRC Website

text

Vito A. Kaminskas Site Vice President DTE Energy Company 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.6515 Fax: 734.586.4172 Email: kaminskasv@dteenergy.com DTE Energy-10 CFR 50.73 May 5, 2015 NRC-15-0051 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington D C 20555-0001

Reference:

Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43

Subject:

Licensee Event Report (LER) No. 2015-002 Pursuant to 10 CFR 50.73 (a)(2)(v)(D) and 10 CFR 50.73(a)(2)(vii), DTE Electric Company is submitting LER No. 2015-002, Loss of both Divisions of the Residual Heat Removal Low Pressure Coolant Injection Functions due to 480 Volt Swing Bus Inoperable.

No commitments are being made in this LER.

Should you have any questions or require additional information, please contact Mr.

Christopher R. Robinson of my staff at (734) 586-5076.

Sincerely, Vito A. Ka inskas Enclosure cc:

NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 5, Region III Regional Administrator, Region III Michigan Public Service Commission Regulated Energy Division (kindschl@michigan.gov)

Enclosure to NRC-15-0051 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 LER 2015-002, Loss of both Divisions of the Residual Heat Removal Low Pressure Coolant Injection Functions due to 480 Volt Swing Bus Inoperable

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3160-0104 EXPIRES: 01/31/2017 (02-2014)

Estimated burden per response to comply with this mandatory collection request 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.

Reported lessons learned are incorporated into the licensing process and fed back to industry.

Send comments regarding burden estimate to the FOIA, Privacy and Information Collections a LBranch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by LICENSEE EVENT REPORT (LER) intemet e-mail to infocollectsResource@nrc.gov, and to the Desk Officer, Ofice of Information and (See Page 2 for required number of Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB digits/characters for each block) control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

3. PAGE Fermi 2 05000 341 1 OF 3

4. TITLE Loss of both Divisions of the Residual Heat Removal Low Pressure Coolant Injection Functions due to 480 Volt Swing Bus Inoperable

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR FACILTYNAME 00K ETNUMBER NUMBER_

NO 05000 IFACILITY NAME DOCKET NUMBER 03 09 2015 2015 -

002 00 05 05 2015 05000

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)

E 20.2201(b)

Q 20.2203(a)(3)(i)

Q 50.73(a)(2)(i)(C)

[

50.73(a)(2)(vii) 1 20.2201(d)

E 20.2203(a)(3)(ii)

E 50.73(a)(2)(ii)(A)

E 50.73(a)(2)(vii)(A) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.36(c)(1)(i)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)

10. POWER LEVEL L 20.2203(a)(2)(ii)

L 50.36(c)(1)(ii)(A)

E 50.73(a)(2)(iv)(A)

[

50.73(a)(2)(x) 20.2203(a)(2)(iii)

J 50.36(c)(2)

E 50.73(a)(2)(v)(A)

[

73.71(a)(4) 100 20.2203(a)(2)(iv)

E 50.46(a)(3)(ii)

E 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(v)

E 50.73(a)(2)(i)(A)

E 50.73(a)(2)(v)(C)

E OTHER 20.2203(a)(2)(vi)

E 50.73(a)(2)(i)(B)

/J 50.73(a)(2)(v)(D)

• ciynAbract below or in

12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT TELEPHONE NUMBER (include Area Code)

David G. Coseo - Supervisor, Nuclear Compliance (734) 586-4273CAUSE SYSTEM COMPONENT MANU-REPORTABLE

CAUSE

SYSTEM COMPONENT MANU REPORTABLE FACTURER TO EPIX FACTURER TOERIX B

BO CNTR G182 Y

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR YES (If yes, complete 15. EXPECTED SUBMISSION DATE)

NO SUDMISSION ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)

On March 09, 2015, a surveillance test of the 480V Swing Bus 72CF Automatic Throwover Scheme was being conducted. At 1521, the alternate power supply breaker failed to close as expected after the normal power supply breaker was opened, resulting in a loss of power to both Reactor Recirculation (RR) pump discharge valves and both divisions of Residual Hear Removal (RHR) Low Pressure Coolant (LPCI) injection valves. The 72CF throwover scheme was declared inoperable and Limiting Condition for Operation (LCO) 3.0.3 was entered. Reactor power was reduced in preparation for meeting the requirement to be in MODE 2 within 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />. 72CF was tagged out to support troubleshooting and repair in accordance with plant procedures.

Troubleshooting found a permissive contact in the close circuit for the alternate power supply breaker to be in the incorrect state. The contact was cleaned and the equipment was returned to service and tested successfully. Following successful completion of the surveillance testing, the throwover scheme was declared operable and LCO 3.0.3 was exited before the 7 hour8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> requirement to be in MODE 2 per LCO 3.0.3.

NRC FORM 366 102-2014)

Initial Plant Conditions

Mode 1

Reactor Power 100 percent Description of the Event:

On March 09, 2015, the monthly Technical Specifications (TS) surveillance test, SR. 3.5.1.2, of the 480V electrical swing bus [BU]

72CF Automatic Throwover scheme was being conducted. At 1521, the alternate power supply breaker failed to close as expected after the normal power supply breaker was opened, resulting in a loss of power to Reactor Recirculation (RR) Pump [AD] discharge valves and both divisions of Residual Heat Removal (RHR) Low Pressure Coolant Injection (LPCI) [BU] Injection Valves [INV]. The 72CF throwover scheme was declared inoperable. At 1521, LCO 3.5.1, Emergency Core Cooling Systems (ECCS) - Operating, was declared not met which required entry in LCO 3.0.3. Reactor power was reduced from 100% to 81% in preparation for meeting the requirement to be in MODE 2 within 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />. The loss of both divisions of RHR LPCI injection valves is reportable under 10 CFR 50.73(a)(2)(v)(D), any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident and 10 CFR 50.73(a)(2)(vii), any event where a single cause or condition caused at least one independent train or channel to become inoperable in multiple systems or two independent trains or channels to become inoperable in a single system designed to mitigate the consequences of an accident. Notifications for a 4-hour non-emergency 10 CFR 50.72(b)(2)(i) for the initiation of any nuclear plant shutdown required by the plant's Technical Specifications and an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> non-emergency 10 CFR 50.72(b)(3)(v) for any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident were completed.

Troubleshooting found a permissive contact in the close circuit for the alternate power supply breaker to be in the incorrect state.

Oxidation was found to be the likely cause of the degraded condition of the contact.

Operations de-energized and tagged out the 72CF Throwover scheme to support troubleshooting and maintenance activities in accordance with plant procedures. To clean the oxidation from the contacts, the contacts were de-termed and cleaned. Following this maintenance activity, Post Maintenance Testing was completed satisfactorily for the contact, and LCO 3.0.3 was exited at 2211 on March 09, 2015 after successful completion of SR 3.5.1,2. The successful completion of the 72CF Throwover Scheme surveillance test provided reasonable assurance that this contact will continue to perform its design function.

Significant Safety Consequences and Implications

The purpose of Technical Specification 3.5.1, is to limit the release of radioactive materials to the environment following a Loss of Coolant Accident (LOCA). AC and DC electrical power is required for Engineered Safety Features to function during any analyzed accident with a loss of off site power, neither of which occurred coincident with this event.

Maintaining the required Division 1 and 2 AC and DC electrical power distribution subsystems Operable ensures the RHR LPCI system can automatically supply LPCI water to the reactor core after the reactor pressure has been reduced to less than the RHR System discharge pressure following a LOCA.

While the 72CF 480V Swing Bus was inoperable, the automatic transfer required between the two safety-related divisions at the 480V distribution level was lost. The Swing Bus is designed for normal feed from Division I Essential Safety Systems (ESS) Bus 72C through two normally closed series contactors, with the standby feed coming from Division 2 ESS Bus 72F through two normally open contactors. These contactors will either close or open automatically as a result of the operational status of the associated breaker.

With the auxiliary contact in a degraded condition likely due to oxidation, the alternate power supply breaker was unable to close, resulting in both RR pump discharge valves and both divisions of RHR LPCI injection valves without their 480V power source. This impacted all RHR LPCI functions. No loss of power to the plant occurred and Divisions I and 2 of Core Spray (CS) and High Pressure Coolant Injection (HPCI) ECCS were available at the time of the event. In addition, the affected valves could have been energized by their normal power source, 72C, at any time during this event by the operating crew, therefore, this event has minor

Cause of the Event

The most likely cause was found to be oxidation which caused the degraded condition of the auxiliary contact.

Corrective Actions

The contact was cleaned. The successful completion of the operability surveillance demonstrated a reasonable assurance that this contact will continue to perform its design function.

Additional Information

A.

Failed Component: Auxiliary Contact Function: Interlock Manufacturer: ITE-Gould Model Number: 5642-DUGAB Failure Cause: Oxidation of the Contacts B.

Previous Licensee Event Reports (LERs) on Similar Problems:

There are no similar previous events within the past five years.